Mixing effects and hydrodynamics of vortex rings

Rohatgi, Aashish; Baird, M. H. I.; Wairegi, T.

doi:10.1002/cjce.5450570403

Cited by 5 publications

(3 citation statements)

References 6 publications

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“…Depending on the volume of addition of heavy density fluid to the agitated bulk, there would be a change in the center of mass and hence, a change in the potential energy of the system. This change can be given as (Van de Vusse, 1955a;Rohatgi et al, 1979):…”

Section: Energy Efficiency Analysismentioning

confidence: 99%

“…The values of energy efficiency obtained in the present work are quite similar to those obtained in the work of Ahmad et al (1988). Rohatgi et al (1979) have also obtained the values of energy efficiency in the range of 0.3 to 1.1%. The values of energy efficiency are inversely proportional to the speed of rotation and hence, operation at lower speeds will be preferred but care should be taken that the operation does not fall into gravity controlled regime or the intermediate regime due to lower speeds.…”

Section: = Elmentioning

confidence: 99%

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Mixing of miscible liquids with density differences: Effect of volume and density of the tracer fluid

Gogate

Pandit

1999

Can J Chem Eng

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The effect on the mixing time of the density difference between the tracer fluid and the bulk, the type and geometry of the impeller, and the amount of the fluid added as a tracer, has been investigated in a tank with diameter of 0.3 1 m. The amount of tracer pulse has been varied in the range of 2 to 8% of the bulk volume and the density difference between two fluids has been varied in the range of 54 to 145 kg/m3. A generalized correlation has been developed for the prediction of dimensionless mixing time (NO) in terms of amount of the tracer fluid, density differences between the bulk and the tracer liquid and the pumping effectiveness of the impeller. A pitched blade downflow turbine with diameter as small as possible is the most energy efficient among the impellers studied in this work.L'effet sur le temps de melange de la difference de masse volumique entre le fluide traceur et le milieu en masse, du type de turbine et de sa geometrie et de la quantite de fluide ajoute comme traceur, a ete etudie dans un reservoir de 0,3 1 m de diametre. On a fait varier la quantite de traceur entre 2 et 8% du volume apparent et la difference de masse volumique entre deux fluides entre 54 et 145kg/m3. Une correlation generalisee a ete mise au point pour la prediction du temps de melange adimensionnel (NO) en termes de quantite de fluide traceur, de differences de masse volumique entre le milieu et le fluide traceur et de I'efficacite de pompage de la turbine. La turbine a ecoulement descendant a lames inclinees d'un diametre aussi petit que possible est la plus efficace en termes d'energie des turbines etudiees dans ce travail.Keywords: mixing time, miscible liquids, volume of tracer pulse, density difference.he mixing of miscible liquids with different physical T properties is a common operation in many chemical and food processing industries. The applications of such a mixing process range from the mixing of various gasoline fractions in large storage tanks to the homogenization of ingredient fluids in soft drinks production or the blending of domestic detergent products or paints. Mixing across density interfaces also occurs in other contexts outside mainstream chemical engineering, e.g. in dense gas dispersion, mixing in the oceanic thermocline, etc.The mixing operation across density andor viscosity barriers can be broadly divided into two types, viz. a mixing operation involving the addition of a small amount of the liquid with a difference in the physical properties, into a bulk of another liquid which is agitated in turbulent condition by mechanical stirrer or, alternatively, a mixing of two stratified layers (stratification is as a result of the large difference in the density and/or viscosity of the two fluids).The two liquids are fully miscible, but for complete homogenization the effects of viscous and buoyancy forces must be overcome by the inertial forces generated by the impeller. When the two fluids to be mixed have large differences in density and viscosity, very long mixing times are observed resulting in ...

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Section: Energy Efficiency Analysismentioning

confidence: 99%

Section: = Elmentioning

confidence: 99%

Mixing of miscible liquids with density differences: Effect of volume and density of the tracer fluid

Gogate

Pandit

1999

Can J Chem Eng

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“…On the laboratory scale, the vortex rings were found effective in mixing of stratified liquids and in agitating a liquid surface to promote gas absorption. The significant contributions in this regard derive from the experiments and analyses done by Professor Baird and his colleagues at the University of McMaster (Rao et al, Rohtagi et al, Baird and Rohtagi, Latto et al, Ni et al and Latto). Ref describes the recent industrial applications of vortex rings.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Solution of the Virtual Mass Coefficient of a Vortex Ring Moving in a Fluid

Kendoush

2008

Ind. Eng. Chem. Res.

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Gas absorption at a liquid surface agitated by vortex rings

Rohatgi

Baird

1981

Can J Chem Eng

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Underwater vortex rings have been formed at orifices of between 25.4 and 63.5 mm diameter and projected upwards at the surface of the water. The conditions of ring formation at which significant surface deformation occnrs have been correlated. The absorption of pure carbon dioxide by the water surface with impinging vortex rings has been measured and related to the following variables: time of fluid impulse through the orifice, orifice diameter, volume of displaced liquid, and depth of submergence. A simplified inass transfer model based on the penetration theory approximately correlates the data.he ability of ring vortices to travel over long

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Mixing effects and hydrodynamics of vortex rings

Cited by 5 publications

References 6 publications

Mixing of miscible liquids with density differences: Effect of volume and density of the tracer fluid

Mixing of miscible liquids with density differences: Effect of volume and density of the tracer fluid

Hydrodynamic Solution of the Virtual Mass Coefficient of a Vortex Ring Moving in a Fluid

Gas absorption at a liquid surface agitated by vortex rings

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